In today's consumer electronics, such as liquid crystal displays (LCD), digital cameras, and laptop computers, etc., switch-mode voltage regulator integrated circuit devices (IC devices) are required to deliver a large amount of current and use very low supply voltage. However, large current is particularly sensitive to interconnection resistance. That is, power efficiency of an IC device is degraded because high conduction loss converts a large current into heat. There are three main areas in an integrated circuit device where interconnection resistance can be reduced: in the circuit package, in the component, and in the interconnects. Among them, the circuit package and the interconnects are the most important factors that contribute to high interconnection resistance. This is especially true when the ON drain to source resistance (RDS(ON)) has decreased due to improvement in the semiconductor manufacturing process. Therefore, IC devices having high-power transistors that achieve low interconnection resistance is crucial to the performance and operability of today consumer electronics.
The conventional method of placing devices in parallel to reduce interconnection resistance results in larger package size. This is antithetical to the miniaturization trend of today's electronic devices. Furthermore, this conventional method necessitates interconnecting these parallel devices by wire bonding, thereby further introducing high interconnection resistance, parasitic resistance, and parasitic inductance to the integrated circuits. Other prior arts attempt to reduce interconnection resistance by using low resistance materials, such as gold or the like. However, this prior art method has only achieved limited results in carrying high current and it has high production costs. Yet other prior art aims to reduce interconnection resistance by using flip chip interconnection ball grid array (FC-BGA) techniques to interconnect the high power integrated circuit die to the lead frame. Still, this technique does not sufficiently reduce the interconnection resistance to enable an IC device to provide the large current required by today consumer electronics.